For a history of three thousand years, Chinese people have been using chopsticks for eating. FIGS. 1 and 2 show a kind of conventional chopsticks, consisting of a rod-shaped upper chopstick member 10 and a rod-shaped lower chopstick member 20. The head 18 of the upper chopstick member and the head 28 of the lower chopstick member are used for gripping food. The tails 19 and 29 of the two chopstick members are opposite of the heads 18 and 28, respectively. The surfaces of the upper chopstick member and the lower chopstick member which touch the thumb are called the front surfaces 11, 21 (see FIG. 1); the surfaces on the top are called the top surfaces 12, 22; the surfaces opposite to the front surfaces are called the back surfaces 13, 23 (see FIG. 2); and the surfaces on the bottom (not shown) are called the bottom surfaces. The side of the thumb near to the direction of the radius bone of the forearm is called the radial side 33 of the thumb, and the side of the thumb near to the direction of the ulna bone of the forearm is called the ulnar side 34 of the thumb. For the chopsticks having cross-sections other than square or rectangle, it is readily understood that the chopsticks can be similarly deemed as having the above-mentioned surfaces.
The correct chopstick holding status is shown in FIG. 1. When the chopsticks are correctly held, the first section 61 of the ring finger supports the back of the lower chopstick member, the base 48 (and the location therebelow) of the third section 43 of the index finger touches the back surface of the lower chopstick member, and the second section 32 of the thumb presses the front surface of the lower chopstick member. Thus the lower chopstick member 20 is firmly gripped through the three regions, so that it cannot be movable relative to the hand. In contrast, the upper chopstick member 10 is movable. The first section 41 of the index finger together with the first section 51 of the middle finger grips the upper chopstick member, allowing an up-and-down motion, such that the upper chopstick member 10 can open and close towards the lower chopstick member 20, achieving the function of food gripping. The third section 43 of the index finger touches the back of the upper chopstick member. The first section 31 of the thumb presses the front surface of the upper chopstick member. The two sections 31, 32 of the thumb should not move relative to the lower chopstick member.
Currently, in order to hold the chopsticks in a more stable manner, some chopsticks are provided with a hinge mechanism for connecting the upper and the lower chopstick members. An example can be found in FIG. 3. Specifically, as shown in FIG. 3, the lower chopstick member 20 is provided with a hinge, which consists of a column 121 vertically extending from the lower chopstick member 20 and a hinge head, i.e., a C-shaped element 122, located at the top of the column 121. The upper chopstick member 10 is provided with a hinge hole 92, which is a through hole but with a pivot (not shown) arranged therein, the longitudinal axis of the pivot being perpendicular to that of the upper chopstick member 10. In assembly status, the pivot of the upper chopstick member 10 is received within the inner chamber 123 of the C-shaped element 122, so that the C-shaped element 122 can turn around the pivot. In this way, the two chopstick members are connected with one another but can still be opened or closed relative to each other. Therefore, the chopsticks can be held in a more stable manner.
However, there are two major problems in this kind of structure. On one hand, the hinge hole 92 reduces the thickness of the front wall 91 and back wall 93 of the upper chopstick member 10, which are rather thin per se. On the other hand, the thickness of the C-shaped element 122 is also undesirably limited by the size of the hinge hole 92, so that the C-shaped element 122 cannot be designed with a large size. The thin walls 91, 93 of the upper chopstick member 10 together with the thin C-shaped element 122 result in a fragile structure.
Moreover, in use the two chopstick members form a lever, so that the torque exerted on the hinge would be significant. When the chopsticks are abusively used (especially by children), this torque is even greater. In this case, a fragile hinge would be broken easily. Broken parts pose potentially serious risk of ingestion and choking injuries, and may lead to suffocation and death of children, and sicknesses for both children and adults as well. Also, the breakage may produce hazardous points and sharp edges which damage the body, such as the skins and eyes of users, both children and adults. It is difficult to pass the torque tests required by safety regulations in many countries.